Spices Halt Growth of Cancer Stem Cells

According to a new study in the journal Breast Cancer Research and Treatment, compounds derived from turmeric and pepper inhibit the growth of cancer stem cells in culture, which could be a critical step in fighting the disease. The research builds on previous studies which have suggested a therapeutic effect from the spices, but this study is the first to show that the mechanism behind this may be the inhibition of the stem cell cycle.

“If we can limit the number of stem cells, we can limit the number of cells with potential to form tumors,” says lead researcher Madhuri Kakarala.

Additionally, the researchers found that the spice extracts showed no toxicity against normal cells – that is, they did not harm the healthy breast cells, an important consideration in a potential cancer treatment.

The authors do caution that consuming large amounts of the spices is not warranted at this time, as there is no evidence that this would be beneficial, and it could even be dangerous.

In the current study, the researcher applied a mixture of curcumin and piperline (derived from turmeric and pepper, respectively) to breast cancer cells at concentrations roughly 20 times what would be consumed through the diet under normal conditions. They found that piperline boosted the effect of curcumin, and the two compounds together halted the stem cells’ regeneration cycle, which is key in the growth and proliferation of cancer. Current chemotherapy treatments attack the cancer cells themselves, rather than the stem cells, but researchers have felt that targeting stem cells may be the more promising method.

Additionally, the researchers found that the spice extracts showed no toxicity against normal cells – that is, they did not harm the healthy breast cells, an important consideration in a potential cancer treatment. Kakarala says that "[w]omen at high risk of breast cancer right now can choose to take the drugs tamoxifen or raloxifene for prevention, but most women won't take these drugs because there is too much toxicity. The concept that dietary compounds can help is attractive, and curcumin and piperine appear to have very low toxicity.”

Another benefit in treatments that attack stem cells rather than cancer cells is that breast cancers that are both estrogen−sensitive and insensitive would be affected by such a therapy. Anti−cancer drugs like those Kakarala mention above are designed to affect only estrogen−sensitive forms of cancer, which are typically not the most deadly forms.

The next step for the researchers is to begin a Phase I clinical trial, which is expected to initiate in early 2010, and will explore the doses of the compounds that can safely be administered to humans.

The study was conducted by researchers at the University of Michigan’s Comprehensive Cancer Center.